Lady X., after walking in a wood near her house in Ireland, found that
she had lost an important key. She dreamed that it was lying at the
root of a certain tree, where she found it next day, and her theory is
the same as that of Mr. A., the o... Read more of The Lost Key at Scary Stories.ca

The Three Great Classes Of Food-fuel

Food is Fuel. Now what is the chief quality which makes one kind of
food preferable to another? As our body machine runs entirely upon the
energy or strength which it gets out of its food, a good food must
have plenty of fuel value; that is to say, it must be capable of
burning and giving off heat and steaming-power. Other things being
equal, the more it has of this fuel value, the more desirable and
valuable it will be as a food.

From this point of view, foods may be roughly classified, after the
fashion of the materials needed to build a fire in a grate or stove, as
Coal foods, Kindling foods, and Paper foods. Although coal, kindling,
and paper are of very different fuel values, they are all necessary to
start the fire in the grate and to keep it burning properly. Moreover,
any one of them would keep a fire going alone, after a fashion, provided
that you had a grate or furnace large enough to burn it in, and could
shovel it in fast enough; and the same is true, to a certain degree, of
the foods in the body.

How to Judge the Fuel Value of Foods. One of the best ways of roughly
determining whether a given food belongs in the Coal, the Kindling, or
the Paper class, is to take a handful or spoonful of it, dry it
thoroughly by some means,--evaporating, or driving off the water,--and
then throw what is left into a fire and see how it will burn. A piece of
beef, for instance, would shrink a good deal in drying; but about
one-third of it would be left, and this dried beef would burn quite
briskly and would last for some time in the fire. A piece of bread of
the same size would not shrink so much, but would lose about the same
proportion of its weight; and it also would burn with a clear, hot
flame, though not quite so long as the beef. A piece of fat of the same
size would shrink very little in drying and would burn with a bright,
hot flame, nearly twice as long as either the beef or the bread. These
would all be classed as Coal foods.

Then if we were to dry a slice of apple, it would shrink down into a
little leathery shaving; and this, when thrown into the fire, would burn
with a smudgy kind of flame, give off very little heat, and soon
smoulder away. A piece of raw potato of the same size would shrink even
more, but would give a hotter and cleaner flame. A leaf of cabbage, or a
piece of beet-root, or four or five large strawberries would shrivel
away in the drying almost to nothing and, if thoroughly dried, would
disappear in a flash when thrown on the fire. These, then, except the
potato, we should regard as Kindling foods.

But it would take a large handful of lettuce leaves, or a big cup of
beef-tea, or a good-sized bowl of soup, or a big cucumber, or a gallon
of tea or coffee, to leave sufficient solid remains when completely
dried, to make more than a flash when thrown into the fire. These, then,
are Paper foods, with little fuel value.